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S4.74 Journal of Plant Pathology (2010), 92 (4, Supplement), S4.71-S4.105 mass spectrometry analyses showed that the MW of the protein was higher than that expected for CU. This protein was purified and characterized. Applying Edmann sequencing and Genome Walking techniques, we obtained a partial nucleotide sequence of the gene and an amino acid sequence of the protein, that were different from those known for CU. Our results show that isolates of Geosmithia spp. harbour two different hydrophobin genes: one, homologous to the cu gene from O. novo-ulmi, could have been acquired by HGT between the two fungal species, as they occupy the same habitat in elm trees. The other gene codes for a new hydrophobin, named Geo1, with a good homology level to the O. novo-ulmi CU protein. ACTIVITY OF THE MICROBIAL CONTROL AGENT BACILLUS SUBTILIS STRAIN QST 713 AGAINST BACTE- RIAL CANKER OF KIWIFRUIT. E. Biondi 1 , S. Mucini 1 , C. Lucchese 1 , E. Ladurner 2 , M. Benuzzi 2 , P. Minardi 3 , U. Mazzucchi 1 . 1 Dipartimento di Scienze e Tecnologie Agroambientali, Sezione di Patologia Vegetale, Università degli Studi, Viale Fanin 40, 40127 Bologna, Italy. 2 Intrachem Bio Italia, Servizio Tecnico, Ricerca e Sviluppo, Via Calcinaro 2085, 47023 Cesena, Italy. 3 Dipartimento di Morfofisiologia Veterinaria e Produzioni Animali, Università degli Studi, Via Tolara di Sopra 50, 40064 Ozzano dell’Emilia (BO), Italy. E-mail: umberto.mazzucchi@unibo.it Bacterial canker of kiwifruit, caused by Pseudomonas syringae pv. actinidiae (Psa), became relevant, especially in 2008 and 2009. Epidemics occurred in Lazio and Emilia Romagna (central and northern Italy) and the causal organisms were identified on the basis of phenotypic and genomic characteristics. In Italy, the control of bacterial canker relies mainly on agronomic prophylactic measures and on the use of copper-based products. In this study, we investigated the ability of Bacillus subtilis strain QST-713 (Serenade Max) to inhibit the growth of two different Psa strains in vitro, and its ability to survive and reduce the population of two rifampicin resistant pathogen strains on female flowers of Actinidia chinensis and A. deliciosa. The microbial control agent was able to survive on female flowers of both Actinidia species, reaching a population of ca. 10 5 CFU/flower 48 and 96 h after application. Moreover, the antagonist reduced the Psa population on A. chinensis flowers by more than one order of magnitude 48 h after its application. These preliminary results indicate that B. subtilis strain QST 713 may be a promising tool for the biological control of bacterial canker of kiwifruit, and provide insights into the interaction between the microbial control agent and Psa. ANTIFUNGAL ACTIVITY OF THREE NOVEL SAPONINS FROM ALLIUM CEPA. G. Bonanomi 1 , A. Gargiulo 1 , V. Antignani 1 , V. Lanzotti 2 , F. Scala 1 . 1 Dipartimento di Arboricoltura, Botanica e Patologia Vegetale, Università degli Studi di Napoli“Federico II”, Via Università 100, 80055 Portici (NA), Italy. 2 Dipartimento di Scienze degli Alimenti, Università degli Studi di Napoli “Federico II”, Via Università 100, 80055 Portici (NA), Italy. E-mail: giuliano.bonanomi@unina.it During their life cycle plants interact with a wide range of different microbial species, including pathogens. Thousands of diverse natural products are produced by plants and many of these are involved in plant defence. The phytochemical diversity of antimicrobial compounds include terpenoids, phenolics, phenylpropanoids, stilbens, alkaloids, glucosinolates, indole and saponins. In this study, the effects of three novel saponins (ACE15G3, ACE15E, ACE15D4) isolated from Allium cepa were tested on soil-borne pathogens (Fusarium oxysporum f. sp. lycopersici, Rhizoctonia solani and Sclerotium cepivorum), air-borne pathogens (Alternaria alternata, Aspergillus niger, Botrytis cinerea, Mucor sp., Phomopsis sp.) and two antagonistic fungi (Trichoderma atroviride and T. harzianum). Antifungal activity of all three saponins increases with their concentration and varied with the following rank: ACE15G3 > ACE15E ~ ACE15D4. F. oxysporum f. sp. lycopersici, S. cepivorum and R. solani were very little affected by saponins. Among the other fungi, B. cinerea and the two Trichoderma species were the most sensitive. We found a significant synergism in the antifungal activity of the three saponins against B. cinerea. Growth of this fungus was strongly inhibited when the three saponins were applied in combination. PLANT LITTER PHYTOTOXICITY AND SOIL-BORNE PATHOGENS CAN EXPLAIN TREE DIVERSITY GRADI- ENT AT GLOBAL SCALE. G. Bonanomi 1 , F. Giannino 2 , G. Incerti 4 , S. C. Dekker 3 , M. Rietkerk 3 , S. Mazzoleni 1 . 1 Dipartimento di Arboricoltura, Botanica e Patologia Vegetale, Università degli Studi di Napoli “Federico II”, Via Università 100, 80055 Portici (NA), Italy. 2 Dipartimento di Ingegneria Agraria e Agronomia del Territorio, Università degli Studi di Napoli “Federico II”, Via Università 100, 80055 Portici (NA), Italy. 3 Department of Environmental Sciences, Copernicus Institute, Utrecht University, PO Box 80115, 3508 TC Utrecht, The Netherlands. 4 Dipartimento di Scienze della Vita, Università degli Studi, Via Giorgieri 10, 34127 Trieste, Italy. E-mail: giuliano.bonanomi@unina.it The diversity of plant species increases from the poles to the equator ranging from almost monospecific forests at high latitude, to intermediate species richness in temperate climates, to the hyper-diverse tropical forests. For plants in aquatic ecosystems, however, this does not occur. Current theories based on resources competition cannot explain such latitudinal patterns of plant diversity. Moreover, the co-occurrence of hyper-diverse stands in lowland terra firma forests and almost monospecific stands in mangroves and gallery riparian vegetation within the tropics remains enigmatic. Here we present a new mathematical model in which, besides the positive feedback of plant growth by nutrients release, litter decomposition and associated changes in soil microbial communities build up a species-specific negative feedback due to soil-borne pathogens and phytotoxicity released by the decaying plant litter. We validated the model by comparing it with extensive published data sets collected both across and within latitudinal or climatic zones. The model predicts correctly the number of tree species, their relative abundance as well as their biomass production in all environmental conditions providing a putative explanation also for the diversity variations observed within the tropics. The model advances in the direction of a unifying ecosystem theory and demonstrates a mechanistic link between the carbon cycle, the soil microbial communities and the tree diversity patterns. DISCOVERY OF NEW PHLOMIS SPECIES NATURALLY INFECTED WITH PHLOMIS MOTTLE VIRUS. D. Boscia 1 , P. Saldarelli 1 , A. De Stradis 1 , C. Vovlas 2 . 1 Istituto di Virologia Vegetale del CNR, UO Bari, Via Amendola 165/A, 70126 Bari, Italy. 2 Dipartimento di Protezione delle Piante e Microbiologia Applicata, Università degli Studi “Aldo Moro”, Via Amendola 165/A, 70126 Bari, Italy. E-mail: d.boscia@ba.ivv.cnr.it Phlomis mottle virus (PhMV), a putative member of the family Flexiviridae, was isolated in 2008 from Phlomis fruticosa L.
Journal of Plant Pathology (2010), 92 (4, Supplement), S4.71-S4.105 S4.75 (family Lamiaceae), a native Mediterranean plant widespread in the Greek Ionian islands and Epirus, on which it causes mottling and deformation of the leaves. More recently, similar symptoms were observed in five species of Phlomis, namely P. chrysophylla Boiss., P. italica L., P. purpurea L., P. viscosa Poir., and P. fruticosa growing in the Botanical Garden of the University of Bari. Leaf samples were collected, processed for observation in the electron microscope, and subjected to RT-PCR analysis using a set of the already described primers FloNAB-FloNABr. Immunoelectron microscopy (IEM) assays were also done using a polyclonal antiserum raised in rabbits immunized with purified PhMV particles. Electron microscope observation of leaf dips from all Phlomis species revealed the consistent presence of filamentous flexuous particles ca. 850 nm long, resembling virions of PhMV, which were decorated by the antiserum to PhMV. RT-PCR assays amplified a single product of the expected size of 465 bp from all tested species. The results of this investigation widen the natural host range and geographical distribution of PhMV. PRELIMINARY RESULTS ON DISTRIBUTION AND DI- VERSITY OF GRAPEVINE YELLOWS IN TUSCANY. H. Bouyahia 1 , D. Rizzo 2 , S. Paltrinieri 3 , M. Della Bartola 1 , P. Braccini 2 , C. Milano 4 , A. Materazzi 1 , A. Bertaccini 3 . 1 Dipartimento di Coltivazione e Difesa delle Specie Legnose “G. Scaramuzzi”, Sezione di Patologia Vegetale, Università degli Studi, Via del Borghetto 80, 56124, Pisa, Italy. 2 Agenzia Regionale per lo Sviluppo e l’Innovazione nel Settore Agricolo-Forestale (ARSIA), Laboratorio di Diagnostica Fitopatologica, Via dei Fiori 8, 51012 Pescia (PT), Italy. 3 Dipartimento di Scienze e Tecnologie Agroambientali, Sezione di Patologia Vegetale, Università degli Studi, Viale Fanin 42, 40127 Bologna, Italy. 4 Dipartimento Provinciale ARPAT, Unità Operativa Agroecosistemi e Alimenti, Via Ponte alle Mosse 211, 50144 Firenze, Italy. E-mail: hbouyahia@agr.unipi.it Grapevine yellows (GY) are an important threat to grapevine industry in Europe. In Italy, GY are mostly represented by Flavescence dorée (FD) and Bois noir (BN) associated with infection by 16SrV and 16SrXII phytoplasma ribosomal groups, respectively. In the frame of a regional strategy aimed at monitoring GY presence, an extensive survey was carried out covering the ten provinces of Tuscany (central Italy), and collecting 585 leaf samples in commercial vineyards inspected in summer 2009. Preference was given to samples showing symptoms referable to GY diseases. To allow tracking of FD-positive samples for uprooting, all vines were marked and localised by “Global Positioning System-GPS”. Nested-PCR and Real-time PCR confirmed that BN is largely the most important GY in Tuscany with an ubiquitous distribution. In fact, it was present in almost all surveyed vineyard with an overall incidence of 70% (418 out of 585 samples tested). Alarming presence of FD was recorded in 23 samples distributed in five provinces, i.e. Arezzo, Massa-Carrara, Florence, Siena and Lucca. Molecular characterization performed with PCR/RFLP analysis on 16S ribosomal and on SecY genes confirmed the presence of either FD-C and FD-D subgroups. FD-D is reported for the first time in Tuscany and is identical to the strain described earlier in France and in Veneto (northern Italy). Further investigations on insect vectors, natural reservoirs and molecular characterization of grapevine-infecting phytoplasmas are needed to monitor and understand the epidemiology GY diseases in Tuscany. EXTENSIVE SURVEY OF VIRUSES INFECTING AN OLIVE VARIETAL COLLECTION IN TUSCANY. H. Bouyahia 1 , D. Rizzo 2 , M. Della Bartola 1 and A. Materazzi 1 1 Dipartimento di Coltivazione e Difesa delle Specie Legnose “G. Scaramuzzi”, Sezione di Patologia vegetale, Università degli Studi, Via del Borghetto 80, 56124 Pisa, Italy. 2 Agenzia Regionale per lo Sviluppo e l’Innovazione nel Settore Agricolo-Forestale (ARSIA), Laboratorio di Diagnostica Fitopatologica, Via dei Fiori 8, 51012 Pescia (PT), Italy. E-mail: hbouyahia@agr.unipi.it The occurrence was investigsted of olive-infecting viruses in the regional varietal collection at the experimental station “Santa Paolina” (CNR-IVALSA, Follonica-Grosseto). Starting from 2004, a total of 245 mother plants belonging to 26 different Tuscan olive varieties were sampled an tested for the presence of nine olive viruses. Largely grown varieties like Leccino, Frantoio and Moraiolo and the less known Correggiolo, Grappolo, Leccio del Corno, etc. were included. Hardwood cuttings taken from different part of the canopy were sampled twice a year (spring and autumn). Cortical scrapings were powdered in liquid nitrogen and total RNA was extracted. During the first years, cDNA synthesis followed by PCR was employed and successively replaced by one-Step RT-PCR for the detection of Arabis mosaic virus (ArMV), Cherry leafroll virus (CLRV) Cucumber mosaic virus (CMV), Olive latent virus 1 (OLV-1), Olive latent virus 2 (OLV-2), Olive ringspot virus (OLRSV), Olive leaf yellowing-associated virus (OLYaV), Strawberry latent ringspot virus (SLRSV) and Tobacco necrosis virus (TNV). Seventeen of 245 samples (6.9%) were infected. Of the nine virus tested for only ArMV, CLRV, OLYaV and SLRSV were detected and no cases of mixed infections were found. Specifically, six mother plants of cvs Leccino, Frantoio and San Fancesco were infected with OLYaV. Ar- MV was found in cvs Correggiolo, Olivastra and Ornellaia and four mother plants of cvs Moraiolo and Maurino were positive to CLRV. Two positive samples to SLRV were detected in cvs Maurino and Grappolo. As previously reported, we confirmed a satisfactory sanitary status of olive germplasm in Tuscany. Work partially funded by “Progetto Interregionale-Qualificazione del vivaismo olivicolo – OLVIVA”. INCIDENCE AND DISTRIBUTION OF BOIS NOIR IN YOUNG VINEYARDS IN TUSCANY. P. Braccini 1 , D. Rizzo 1 , T. Cinelli 2 , G. Marchi 2 . 1 Agenzia Regionale per lo Sviluppo e l’Innovazione nel Settore Agricolo-Forestale (ARSIA), Via Pietrapiana 30, 50121 Firenze, Italy. 2 Dipartimento di Biotecnologie Agrarie, Sezione di Protezione delle Piante, Università degli Studi, Piazzale delle Cascine 28, 50144 Firenze, Italy. E-mail: guido.marchi@ unifi.it The spread of bois noir was monitored from 2005 to 2009 in seven vineyards of cv. Sangiovese established in 2001 in Tuscany (central Italy). In each season the number and position of the vines showing typical symptoms (leaf discolouration, downward rolling of leaves, incomplete lignification of canes, shrivelled bunches) were recorded. Only the presence of 16SrXII-A phytoplasmas was ascertained by PCR analysis on bulk samples of symptomatic leaves. With the purpose of determining the spatial pattern of the disease (random vs. aggregated or clustered), for each year of assessment, field data on annual incidence were analyzed at three spatial levels (hierarchies) including: (i) adjacent vines within the row and across the rows (ordinary runs analysis), (ii) within vines grouped into sampling units (distribution analysis) and (iii) among groups of plants at some distance from one another (SADIE-Spatial Analysis by Distance Indices). As a whole, the pattern of temporal disease incidence showed a similar trend in six of the seven study sites: annual incidence rate progressively decreased from year to year after the first or second
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